Related Questions

A wound rotor induction motor is preferred, as compared to squirrel cage induction motor, when major consideration is
A Slop speed operation
B High starting torque
C Low windage losses
D All of the above
While starting a synchronous motor by induction motor action, field winding is usually
A connected to D.C. supply
B short-circuited by low resistance
C kept open-circuited
D none of the above
A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
A synchronous motor has no slip
B stator supply is not required to produce magnetic field
C mechanical load on the rotor remains constant
D synchronous motor has large airgap
While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
A induction motor torque in field winding
B induction motor torque in damper winding
C eddy current and hysteresis torque in pole faces
D reHetance motor torque due to saliency of the rotor
E all of the above methods
Slip ring motor is preferred over squirrel cage induction motor where
A High starting torque is required
B Load torque is heavy
C Heavy pull out torque is required
D All of the above
The power factor of a synchronous motor is better than that of induction motor because
A stator supply is relieved of responsibility of producing magnetic field
B mechanical load on the motor can be adjusted
C synchronous motor runs at synchronous speed
D synchronous motor has large air gap
An important advantage of a synchronous motor over wound round induction motor is that
A its power factor may be varied at will
B its speed is independent of supply frequency
C its speed may be controlled more easily
D none of the above
The starting torque of a three phase induction motor can be increased by
A Increasing slip
B Increasing current
C Both (A) and (B)
D None of the above
The stating torque of the slip ring induction motor can be increased by adding
A External inductance to the rotor
B External resistance to the rotor
C External capacitance to the rotor
D Both resistance and inductance to rotor
In case the air gap in an induction motor is increased
A The magnetizing current of the rotor will decrease
B The power factor will decrease
C Speed of motor will increase
D The windage losses will increase

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